Request for Comments

A Request for Comments (RFC) document is one of a series of numbered Internet informational documents and standards very widely followed by both commercial software and freeware in the Internet and Unix communities. They are now published under the aegis of the Internet Society (ISOC, an open organization whose mission is developing the Internet for the benefit of people throughout the world) and its technical standards-setting bodies.

The basic communication protocols which the Internet uses to operate are all specified in RFCs, for instance. However, RFCs cover many topics in addition to standards, such as introductions to new research ideas and status memos about the Internet. While few RFCs are standards, almost all Internet standards are recorded in RFCs.


History and current organization

The RFC series of documents on networking began in 1969 as part of the original ARPA wide area networking ARPANET project.

Today, it is the official publication channel for the Internet Engineering Task Force (IETF), the Internet Architecture Board (IAB), and the broader Internet community. RFCs are published by the RFC Editor, who is supported by the ISOC, but is under the general direction of the IAB.

Once published and issued a number, an RFC is never canceled or depublished; it is instead superseded by the publication of a new one. To determine which RFCs are actually active Internet standards and which ones have been superseded, one must consult the official list, Internet Standard 1 (STD 1), which itself is republished regularly as an RFC.

How to obtain RFCs

RFCs can be obtained on the Internet from the RFC Editor [1] (, the IETF [2] (, or many other sites, principally using the Web, but also through anonymous FTP, gopher, and other Internet document-retrieval systems.

Every RFC is available as ASCII text and may be available in other formats, depending on the author. The definitive version of any standards-track specifications is always the ASCII version.

A complete RFC index in text format ( is available from the IETF website. Any published RFC can be directly found by inserting the number into the following URL: (replace # with the RFC number).

How RFCs are made (the RFC process)

The RFCs are produced in a process that is different from that used in formal standards organizations such as ANSI. They can be floated by technical experts acting on their own initiative and reviewed by the Internet at large. Practically speaking, standards-track RFCs are usually produced by experts participating in working groups which first publish what the IETF calls Internet-Drafts; this facilitates initial rounds of review before documents become RFCs.

The RFC tradition of pragmatic, experience-driven, after-the-fact standard writing done by individuals or small working groups has important advantages over the more formal, committee-driven process typical of ANSI or ISO.

Emblematic of some of these advantages is the existence of a flourishing tradition of joke RFCs. Usually at least one a year is published, usually on April Fool's Day.

The RFCs are most remarkable for how well they work - they manage to have neither the ambiguities that are usually rife in informal specifications, nor the committee-perpetrated misfeatures that often haunt formal standards, and they define a network that has grown to truly worldwide proportions.

For more details about RFCs and the RFC process, see RFC 2026, "The Internet Standards Process, Revision 3".


RFC 1, entitled "Host Software", was written by Steve Crocker from the University of California, Los Angeles, and published on April 7, 1969.

The initial RFCs were apparently typewritten and circulated on hard copy among the ARPA researchers. Once ARPANET was fully functional by December 1969, subsequent RFCs were drafted and circulated over the network.

Douglas Engelbart's Augmentation Research Center at SRI was the first Network Information Center as well as one of the first two nodes on the network (the other was UCLA). The sociologist Thierry Bardini has pointed out that ARC personnel authored a large number of the early RFCs.

One advantage of the tradition of never depublishing obsolete RFCs is that they form a continuous historical record of the evolution of Internet standards. Lawyers will notice that this is roughly analogous to the tradition in common law countries (including the United States, where the Internet was born) of never depublishing case opinions, but instead overruling them with new ones.

List of commonly-used RFCs

RFC 768 User Datagram Protocol
RFC 791 Internet Protocol
RFC 792 Control message protocol
RFC 793 Transmission Control Protocol
RFC 821 Simple Mail Transfer Protocol, obsoleted by RFC 2821
RFC 822 Format of e-mail, obsoleted by RFC 2822
RFC 826 Address resolution protocol
RFC 894 IP over Ethernet
RFC 951 Bootstrap Protocol
RFC 959 File Transfer Protocol
RFC 1034 Domain Name System - concepts
RFC 1035 DNS - implementation
RFC 1122 Host Requirements I
RFC 1123 Host Requirements II
RFC 1191 Path MTU discovery
RFC 1256 Router discovery
RFC 1323 High performance TCP
RFC 1350 Trivial File Transfer Protocol
RFC 1403 BGP OSPF Interaction
RFC 1459 Internet Relay Chat Protocol
RFC 1498 Architectural discussion
RFC 1518 CIDR address allocation
RFC 1519 Classless inter-domain routing
RFC 1591 Domain Name Structure
RFC 1661 Point-to-Point Protocol
RFC 1738 Uniform Resource Locators
RFC 1771 A Border Gateway Protocol 4
RFC 1772 BGP application
RFC 1789 Telephone over Internet (obsoleted by current VoIP standards)
RFC 1812 Requirements for IPv4 Routers
RFC 1889 Real-Time transport
RFC 1905 Simple network management protocol
RFC 1907 Simple network management protocol v2 Management information base
RFC 1918 "Network 10"
RFC 1939 Post Office Protocol version 3 (POP3)
RFC 2001 TCP performance extensions
RFC 2026 Internet Standards process
RFC 2046
RFC 2047
RFC 2048
RFC 2049
RFC 2060 Internet Message Access Protocol version 4 (IMAP4), obsoleted by RFC 3501
RFC 2223 Instructions to RFC Authors
RFC 2231 Character Sets
RFC 2401 Security Architecture
RFC 2453 Routing Information Protocol
RFC 2525 TCP Problems
RFC 2535 DNS Security
RFC 2581 TCP congestion control
RFC 2663 Network address translation
RFC 2821 Simple Mail Transfer Protocol
RFC 2822 Format of e-mail
RFC 3010 Network File System
RFC 3031 MPLS architecture
RFC 3066 Language Tags
RFC 3092 Etymology of "Foo"
RFC 3098 Advertise Responsibly Using E-Mail
RFC 3160 Tao of IETF
RFC 3168 ECN
RFC 3261 SIP
RFC 3501 IMAP4rev1

See also

Links to IETF RFCs

Generic RFCs

  • RFC 1718, The Tao of IETF - A Guide for New Attendees of the Internet Engineering Task Force. The IETF Secretariat, G. Malkin. November 1994. (Format: TXT=50477 bytes) (Obsoletes RFC 1539) (Also FYI0017) (Status: INFORMATIONAL)
  • RFC 2026, The Internet Standards Process -- Revision 3. Scott O. Bradner. October 1996. (Format: TXT=86731 bytes) (Obsoletes RFC 1602) (Also BCP0009) (Status: BEST CURRENT PRACTICE)
  • RFC 2555, 30 Years of RFCs. April 1999.

Link-level RFCs

  • RFC 1969, The PPP DES Encryption Protocol (DESE). K. Sklower, G. Meyer. June 1996. (Format: TXT=20383 bytes) (Obsoleted by RFC 2419) (Status: INFORMATIONAL)
  • RFC 2419, The PPP DES Encryption Protocol, Version 2 (DESE-bis). K. Sklower, G. Meyer. September 1998. (Format: TXT=24414 bytes) (Obsoletes RFC 1969) (Status: PROPOSED STANDARD)

Internetwork-level RFCs

  • RFC 791, Internet Protocol. J. Postel. Sep-01-1981. (Format: TXT=97779 bytes) (Obsoletes RFC0760) (Also STD0005) (Status: STANDARD)
  • RFC 3115, Mobile IP Vendor/Organization-Specific Extensions. G. Dommety, K. Leung. April 2001. (Format: TXT=16363 bytes) (Obsoletes RFC 3025) (Status: PROPOSED STANDARD)
  • RFC 1809, Using the Flow Label Field in IPv6. C. Partridge. June 1995. (Format: TXT=13591 bytes) (Status: INFORMATIONAL) The current standard for flow labels in IPv6 is described in RFC 3595.
  • RFC 2644, Changing the Default for Directed Broadcasts in Routers. D. Senie. August 1999. (Format: TXT=6820 bytes) (Updates RFC 1812) (Also BCP0034) (Status: BEST CURRENT PRACTICE)

Host/router requirements RFCs

  • RFC 1009, Requirements for Internet gateways. R.T. Braden, Jon Postel. Jun-01-1987. (Format: TXT=128173 bytes) (Obsoletes RFC 985) (Obsoleted by RFC 1812) (Status: HISTORIC)
  • RFC 1122, Requirements for Internet Hosts - Communication Layers. Robert Braden (editor). October 1989. (Format: TXT=295992 bytes) (Also STD0003) (Status: STANDARD)
  • RFC 1123, Requirements for Internet Hosts - Application and Support. Robert Braden (editor). October 1989. (Format: TXT=245503 bytes) (Updates RFC 822) (Updated by RFC 2181) (Also STD0003) (Status: STANDARD)
  • RFC 1812, Requirements for IP Version 4 Routers. F. Baker. June 1995. (Format: TXT=415740 bytes) (Obsoletes RFC 1716, RFC 1009) (Updated by RFC 2644) (Status: PROPOSED STANDARD)

ISO interoperation RFCs

  • RFC 983, ISO transport arrives on top of the TCP. D.E. Cass, Marshall T. Rose. Apr-01-1986. (Format: TXT=59819 bytes) (Obsoleted by RFC 1006) (Status: UNKNOWN)
  • RFC 1006, ISO transport services on top of the TCP: Version 3. M.T. Rose, D.E. Cass. May-01-1987. (Format: TXT=31935 bytes) (Obsoletes RFC 983) (Updated by RFC 2126) (Also STD0035) (Status: STANDARD)
  • RFC 2126, ISO Transport Service on top of TCP (ITOT). Y. Pouffary, A. Young. March 1997. (Format: TXT=51032 bytes) (Updates RFC 1006) (Status: PROPOSED STANDARD)

Domain Name System RFCs

  • RFC 1591, Domain Name System Structure and Delegation. J. Postel. March 1994. (Format: TXT) (Status: INFORMATIONAL)
  • RFC 1876, A Means for Expressing Location Information in the Domain Name System. C. Davis, Paul Vixie, T. Goodwin, I. Dickinson. January 1996. (Format: TXT=29631 bytes) (Updates RFC 1034, RFC 1035) (Status: EXPERIMENTAL)
This covers the operation of secondary domain name servers.
  • RFC 3008, Domain Name System Security (DNSSEC) Signing Authority. B. Wellington. November 2000. (Format: TXT=13484 bytes) (Updates RFC 2535) (Status: PROPOSED STANDARD)

X.500 RFCs

  • RFC 1632, A Revised Catalog of Available X.500 Implementations. A. Getchell, S. Sataluri, Editors. May 1994. (Format: TXT=124111 bytes) (Obsoletes RFC 1292) (Obsoleted by RFC 2116) (Status: INFORMATIONAL)
See also X.500
  • RFC 2116, X.500 Implementations Catalog-96. C. Apple, K. Rossen. April 1997. (Format: TXT=243994 bytes) (Obsoletes RFC 1632) (Also FYI0011) (Status: NFORMATIONAL)

Network management RFCs

  • RFC 1066, Management Information Base for network management of TCP/IP-based internets. K. McCloghrie, Marshall T. Rose. Aug-01-1988. (Format: TXT=135177 bytes) (Obsoleted by RFC 1156) (Status: UNKNOWN)
  • RFC 1156, Management Information Base for network management of TCP/IP-based internets. K. McCloghrie, Marshall T. Rose. May-01-1990. (Format: TXT=138781 bytes) (Obsoletes RFC 1066) (Status: HISTORIC)
  • RFC 1792, TCP/IPX Connection Mib Specification. T. Sung. April 1995. (Format: TXT=16389 bytes) (Status: EXPERIMENTAL)

E-mail RFCs

This is an important early RFC from the IETF that specified the protocol for transferring e-mail messages between computers on the Internet. Many additions have been made to it, but it remained a standard for many years until obsoleted by RFC 2821 (the number is not a coincidence: it was reserved for this use).
This is an important early RFC from the IETF that specified the format of e-mail messages exchanged between computers on the Internet. Many additions have been made to it, but it remained a standard for many years until obsoleted by RFC 2822 (the number is not a coincidence: it was reserved for this use).
This standard specifies the protocol for transferring e-mail messages between computers on the Internet.
This standard specifies a syntax for text messages that are sent between computer users, within the framework of electronic mail messages. This standard is about text-only messages. The syntax for sending other types of messages, such as binary or structured data, is specified as an extension of this standard by the MIME document series: RFC 2045, RFC 2046, RFC 2047, RFC 2049.
  • RFC 3098, How to Advertise Responsibly Using E-Mail and Newsgroups or - how NOT to $$$$$ MAKE ENEMIES FAST! $$$$$. E. Gavin, D. Eastlake 3rd, S. Hambridge. April 2001. (Format: TXT=64687 bytes) (Also FYI0038) (Status: INFORMATIONAL)

X.400 E-mail RFCs


  • RFC 1521, MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies. N. Borenstein, N. Freed. September 1993. (Format: TXT=187424, PS=393670, PDF=205091 bytes) (Obsoletes RFC 1341) (Obsoleted by RFC 2045, RFC 2046, RFC 2047, RFC 2048, RFC 2049) (Updated by RFC 1590) (Status: DRAFT STANDARD)
  • RFC 2045, Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies. N. Freed, N. Borenstein. November 1996. (Format: TXT=72932 bytes) (Obsoletes RFC 1521, RFC 1522, RFC 1590) (Updated by RFC 2184, RFC 2231) (Status: DRAFT STANDARD)
  • RFC 2046, Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types. N. Freed, N. Borenstein. November 1996. (Format: TXT=105854 bytes) (Obsoletes RFC 1521, RFC 1522, RFC 1590) (Updated by RFC 2646) (Status: DRAFT STANDARD)
  • RFC 2047, MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text. K. Moore. November 1996. (Format: TXT=33262 bytes) (Obsoletes RFC 1521, RFC 1522, RFC 1590) (Updated by RFC 2184, RFC 2231) (Status: DRAFT STANDARD)
RFC 2047 specifies a standard way of encoding non US-ASCII characters into a string that identifies both the character set to use and the actual characters. The result of the encoding will be US-ASCII, and can be transmitted in Internet mail and decoded appropriately on the receiving end. This encoding is necessary in the first place because many characters in non-English languages can not be represented in 7-bit ASCII.
There are some mail clients that are not RFC 2047 Compliant, if you are using one of this clients you are strongly encuraged to change your mail client or to update it to a compliant version:
Eudora 4: Double quote characters are encoded with a Windows codpage and are eight-bit characters. Eudora's MIME headers indicate the MIME type but not 8-bit encoding. Suggest enabling "quoted printable" encoding.
  • RFC 2048, Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures. N. Freed, J. Klensin, Jon Postel. November 1996. (Format: TXT=45033 bytes) (Obsoletes RFC 1521, RFC 1522, RFC 1590) (Updated by RFC 3023) (Also BCP0013) (Status: BEST CURRENT PRACTICE)
  • RFC 2049, Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples. N. Freed, N. Borenstein. November 1996. (Format: TXT=51207 bytes) (Obsoletes RFC 1521, RFC 1522, RFC 1590) (Status: DRAFT STANDARD)
  • RFC 2183, Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field. R. Troost, S. Dorner, K. Moore. August 1997. (Format: TXT=23150 bytes) (Updates RFC 1806) (Updated by RFC 2184, RFC 2231) (Status: PROPOSED STANDARD)
  • RFC 2184, MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations. N. Freed, K. Moore. August 1997. (Format: TXT=17635 bytes) (Obsoleted by RFC 2231) (Updates RFC 2045, RFC 2047, RFC 2183) (Status: PROPOSED STANDARD)
  • RFC 2231, MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations. N. Freed, K. Moore. November 1997. (Format: TXT=19280 bytes) (Obsoletes RFC 2184) (Updates RFC 2045, RFC 2047, RFC 2183) (Status: PROPOSED STANDARD)
  • RFC 2646, The Text/Plain Format Parameter. R. Gellens. August 1999. (Format: TXT=29175 bytes) (Updates RFC 2046) (Status: PROPOSED STANDARD)

April 1st RFCs

See April 1st RFC for complete list

  • RFC 1776 The Address is the Message. Steve Crocker. Apr-01-1995. (Format: TXT=2051 bytes) (Status: INFORMATIONAL)
  • RFC 2549, IP over Avian Carriers with Quality of Service, D. Waitzman. Apr-01-1999. (Format: TXT=9519 bytes) (Updates RFC 1149) (Status: INFORMATIONAL)
  • RFC 3751, Omniscience Protocol Requirements, S. Bradner. Apr-01-2004. (Status: INFORMATIONAL)

Random support RFCs

  • RFC 3023, XML Media Types. M. Murata, S. St.Laurent, D. Kohn. January 2001. (Format: TXT=86011 bytes) (Obsoletes RFC 2376) (Updates RFC 2048) (Status: PROPOSED STANDARD)
  • RFC 3097, RSVP Cryptographic Authentication -- Updated Message Type Value. R. Braden, L. Zhang. April 2001. (Format: TXT=6320 bytes) (Updates RFC 2747) (Status: PROPOSED STANDARD)
  • RFC 2747, RSVP Cryptographic Authentication. F. Baker, B. Lindell, M. Talwar. January 2000. (Format: TXT=49477 bytes) (Updated by RFC 3097) (Status: PROPOSED STANDARD)

Random application RFCs

  • RFC 1789, INETPhone: Telephone Services and Servers on Internet. C. Yang. April 1995. (Format: TXT=14186 bytes) (Status: INFORMATIONAL)
  • RFC 3066, Tags for the Identification of Languages. H. Alvestrand. January 2001. (Format: TXT=26522 bytes) (Obsoletes RFC 1766) (Also BCP0047) (Status: BEST CURRENT PRACTICE)
This provides a way to register extensions of codes for language names in ISO 639. The current reviewer of new tags and maintainer of the registry ( is Michael Everson.
  • RFC 3106, ECML v1.1: Field Specifications for E-Commerce. D. Eastlake, T. Goldstein. April 2001. (Format: TXT=40715 bytes) (Obsoletes RFC 2706) (Status: INFORMATIONAL)

Random RFCs

  • RFC 823 DARPA Internet gateway. R.M. Hinden, A. Sheltzer. Sep-01-1982. (Format: TXT=62620 bytes) (Updates IEN 109, IEN 30) (Status: HISTORIC)
This is a memo and status report of the DARPA Internet Gateway. It deals with two areas: gateway procedures and message formats. Topics include information on the forwarding of internet datagrams, various protocols supported by the gateway, and specific gateway software. Unlike many other RFCs, it does not list any implementation specifics.
  • RFC 824 CRONUS Virtual Local Network. W.I. MacGregor, D.C. Tappan. Aug-25-1982. (Format: TXT=58732 bytes) (Status: UNKNOWN)
  • RFC 3094, Tekelec's Transport Adapter Layer Interface. D. Sprague, R. Benedyk, D. Brendes, J. Keller. April 2001. (Format: TXT=265099 bytes) (Status: INFORMATIONAL)
  • RFC 3675, .sex Considered Dangerous. D. Eastlake 3rd. February 2004.


This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.

External links

da:Request for Comments de:Request for Comments fr:Request for comments id:RFC it:Request for Comments nl:Request For Comments ja:Request for Comments pl:RFC pt:RFC sl:Zahteva po razlagi fi:RFC sv:RFC


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